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Posted: 5/19/2013 8:57:30 AM EDT
| I just finished builing my first (and not last!!) AR. Took it to the range this morning for it's first outing. About 20 rounds into it the rounds failed to feed. I could use the charging handle and pull the bolt back to feen another round, but it wouldn't go past that. It seemed that the magazine was pusing rounds up. Since this is my first try at this, I just want to ensure that I didn't miss something. I know that I've likely left something useful out, but telling you what I know. |
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There are many very knowledgeable people here who will help you. You will need to give more info and pictures are good as well. What gas system, barrel length gas block, buffer, buffer spring etc. Just give the details. It could possibly be undergassed, what type of gas block is on it? Did you put it on or did you buy a complete upper assy? ETA: Also add what ammo you are using, seeings how you got 20 rounds in to it with no issues the gas thing is probably ok. I missed that part...
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Quoted:
There are many very knowledgeable people here who will help you. You will need to give more info and pictures are good as well. What gas system, barrel length gas block, buffer, buffer spring etc. Just give the details. It could possibly be undergassed, what type of gas block is on it? Did you put it on or did you buy a complete upper assy? ETA: Also add what ammo you are using, seeings how you got 20 rounds in to it with no issues the gas thing is probably ok. I missed that part... Ammo I was using is Remington 223 It's got a low profile gas block that I purchased from a local company called BTE. I assembled the rifle and did not get it as a complete upper. Barrel length is 16" and the gas tube is carbine length. One person at the range I go to suggested that the buffer detent might be sticking up too far. Not sure how to repair that. |
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I am huge fan of just standard USGI 20 rounds, now im not saying that is the problem, just trying to narrow things down lets swap mags see if you can feed a full clip out by hand easily, then fire see what happens. If it clears, lets swap back to the anti tilt magpull followers and see if we can replicate the failure. This could be number of things as stated, low gas compression, buffer issue, spring tension, but when you get something like always good to tackle one system at a time. At least that is my opinion. |
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Quoted: What type of gas block? Is it held on by two set screws on the bottom that tighten on to the barrel or is it a clamp kind that you tighten? If set screw did you dimple the barrel using a gas block jig? Is it pinned? I won't try to be the resident expert but I have seen barrels where those set screw gas blocks move when the barrel is not dimpled. You can see the marks on the barrel. If this happens you could block the gas port and it won't cycle properly. I'm not sure what the guy means about the buffer detent being to high? It's purpose is hold the buffer in. I doubt that is the issue.Quoted: There are many very knowledgeable people here who will help you. You will need to give more info and pictures are good as well. What gas system, barrel length gas block, buffer, buffer spring etc. Just give the details. It could possibly be undergassed, what type of gas block is on it? Did you put it on or did you buy a complete upper assy? ETA: Also add what ammo you are using, seeings how you got 20 rounds in to it with no issues the gas thing is probably ok. I missed that part... Ammo I was using is Remington 223 It's got a low profile gas block that I purchased from a local company called BTE. I assembled the rifle and did not get it as a complete upper. Barrel length is 16" and the gas tube is carbine length. One person at the range I go to suggested that the buffer detent might be sticking up too far. Not sure how to repair that. ETA: Maybe he means the buffer is catching on the outer edge (larger diameter) of the buffer detent and not the smaller pin diameter. This would put the buffer a little further back. You could just look at it to see what the buffer is catching on??? It should catch on the pin part of the detent.
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| Gas block has three allen screws on the bottom. I tightened them as much as I could. The bolt carrier group does seem a bit snug. It's difficult to pull back, but it springs forward pretty easily. I just did a half magazine through it and there were a couple of rounds that didn't feed correctly. When ejecting, the brass literally flies away. |
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Quoted: Gas block is probably ok as long as you have it lined up right. Clean it very thoroughly, put some grease on the bolt lugs. Take it out with some good ammo, 193, 855 etc. and see if it cycles. What buffer and spring are you using and what length gas system do you have and what is your barrel length?Gas block has three allen screws on the bottom. I tightened them as much as I could. The bolt carrier group does seem a bit snug. It's difficult to pull back, but it springs forward pretty easily. I just did a half magazine through it and there were a couple of rounds that didn't feed correctly. When ejecting, the brass literally flies away. |
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With a new weapon my experience is most of the time it is insufficient lube.
Bad mags or weak ammo seem to run second. P-mags should be GTG, but it could not hurt to try a GI mag. Try some XM193/XM855 or equivalent. Thoroughly clean and inspect the weapon. I have seen posts of broken gas key screws a lot lately, also look for gas leaks at the gas block, gas tube to GB, and gas key. |
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Check your mags first. I suggest marking each mag with a number. If you have a failure then note which mag is was. If you have multiple failures with the same mag then that could be the problem. Next clean and lube the gun. Many failures on new guns are because it is dirty or not lubed properly.
Is the Ammo factory ammo or reloads? I have found that my reloads don't feed well until I have broken the chamber in. Also give the chamber a good cleaning. Some of the parts sit in dirty warehouses prior to sale. If the bolt is tight when in the forward position, it is possible that it is dirty where the lugs lock in. Moving from that I would check the gas system and buffer system. I start by pulling the bolt. Make sure the gas rings are not lined up. The openings on the 3 rings need to be pointed different directions. Once you check that take the BCG and place it on the bolt face. If the bolt slides into the carrier under its own weight then the gas rings are worn out and need to be replaced (should not be the case on a new BCG). Next I test to make sure gas is coming through the gas tube. First I look to make sure the gas block look lined up. Next I place a round in the chamber ( I do this with the upper separated and no BCG.) I blow into the muzzle end of the bbl and make sure air is coming out of the gas tube. If all that looks good then check the buffer and spring. If you got a rifle length spring accidentally I can cause this problem. I doubt it would have cycled so my guess is that us not the problem. Inspect your lower and make sure that the buffer retaining spring is held down by the lip on the buffer tube. The retaining pin should move up and down when you push it. If you screwed the tube in to far it will rub on the retaining pin and either hold t up or down. Also forgot to mention a bad extractor spring or extractor can also cause that problem ( should not be the case on a new gun.) Other the. That I think I would need pictures or more information. Pictures of the rounds that failed to feed. Pictures of the jam. |
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